RE: A truth telling American President, how refreshing!4 Mar 2021 10:03
"FFP masks can also come with or without valves. The exhalation valve on the mask allows for air and moisture to exit the mask. This makes them more comfortable to wear for extended periods of time. However, a valve does make the mask feel more bulky when on. Also in a clinical setting, when the mask is worn to protect from airborne viruses, the valve is not desirable as it allows for unfiltered air to exit the mask from the wearer. In these situations, an unvalved mask protects both wearer and those around the wearer. If valved masks are the only type available, a surgical mask worn over it may increase the protection to those around the wearer."
:( I've got the wrong kind of mask. Whoops.